What I said is, when someone buys a single item and pays with CC, it takes subjectively 10x longer than buying a single item and paying cash.

If someone brings a cart full of stuff, the scanning time is way longer than the payment process, regardless what method. So it become irrelevant if cash or card.

I have an amex card from Thai amex since 2000. Never had any issue with it and working well. Using it for hotels (not only 5 stars) and department store. Using it online including Air Asia online without any problem. Happened to me 2 times that a payment showed in statement was not made by me (fraud). The first time was an amount of 10,000 USD that was done in Africa. I called the customer services. They asked me to fax them evidences that i was in Thailand (or anywhere else during the period), cut the card in 2 and fax it. I received a brand new card 24h later (I was in Phuket). The second time was sumilar but happen in Bangkok. There was many purchases done in a day that was not looking regular based on my monthly statements ( payments in golf shops... which i am not playing golf). They called me and warned me about those payment). Same thing: i provided them evidence that i was in Phuket during the period. They immediately blocked the credit card and send me a new one 24h later.

Really no issue with Amex Thailand.

Few month ago I received a the monthly statement. I am not using direct debit. I was travelling and forgot to pay the bill. When i came back home, the new statement arrived and i found out that i didn't pay the previous one! I called and explained. They told me that was no issue but system was automaticaly scheduled to block the card in the next few days. I told them i will immediately proceed payment. They told me that in this case they will remove the late payment fees. We were talking about a bill of around 100k THB.

It seems that there is no limit on monthly spending. I used to receive as much as 400k THB statement.

I am using the Gold card and my wife has the "complimentary" gold from me